The present invention relates to a rotor shaft, and more particularly to a rotor shaft having a non-circular cross section. The present invention also relates to a cooling fan using the non-circular rotor shaft, so that a lubricant filled between the rotor shaft and a bearing of the cooling fan can have increased support pressure.
Various kinds of electronic information products, such as computers and the like, are now very popular among people and applied to very wide applications. Due to consumers' demands, the electronic information technology has quickly developed and it has become a significant trend to increase the computing speed and the access capacity of the electronic information products. However, a high amount of heat is also produced when the elements of the electronic information products operate at high speed.
For example, the central processing unit (CPU) of a computer produces the largest part of heat in the computer. When the produced heat gradually increases and accumulates in the computer, it would bring the CPU to have lowered performance. And, when the accumulated heat exceeds the allowable upper limit, it would force the computer to crash or even cause burnout of the computer. Moreover, to solve the problem of electromagnetic wave radiation, most of the important and heat-producing components of the computer are enclosed in a metal case. Thus, it is an important issue as how to quickly guide out and dissipate the heat energy produced by the CPU and other heat-producing elements.
A general way to solve the problem of heat dissipation for CPU is to mount a heat sink and a cooling fan atop the CPU. The heat sink is provided on one side with a plurality of radiating fins, and another opposite side of the heat sink without the radiating fin is in direct contact with the CPU, so that the heat produced by the CPU is transferred to the radiating fins, from where the heat is radiated into the ambient air. The cooling fan cooperates with the heat sink to produce air flows that force the heat to more quickly dissipate into the ambient environment.
The cooling fan includes a seat and a rotor assembly. The seat is formed with a bearing cup, in which at least one bearing is provided. A stator assembly is externally fitted around the bearing cup. The bearing internally defines a shaft space. The rotor assembly includes a hub and a rotor shaft. The hub has a plurality of spaced and radially outward extended blades. The rotor shaft has an end inserted into one side of the hub and another opposite end rotatably received in the shaft space. A lubricant is filled between the rotor shaft and the shaft space of the bearing. When the cooling fan operates, the rotor shaft of the rotor assembly rotates in and relative to the bearing. Since the lubricant provides uneven support pressure when the rotor shaft rotates, the rotor shaft would collide with an inner wall surface of the shaft space to produce noise and vibration, preventing the rotor assembly from operating smoothly. Under these circumstances, the cooling fan would have reduced service life.
A primary object of the present invention is to provide a rotor shaft having a non-circular cross section, so as to reduce the noise, vibration and wearing occurred during the use of the rotor shaft.
Another object of the present invention is to provide a cooling fan that uses a rotor shaft having a non-circular cross section, so as to reduce the noise, vibration and wearing occurred during the operation of the cooling fan.
To achieve the above and other objects, the rotor shaft according to the present invention includes a main body having a central portion and an extension portion. The extension portion includes a plurality of extension sections, which are connected to one another and respectively radially outward extend from the central portion to together define a peripheral surface of the main body. The extension sections respectively radially outward extend from the central portion by a different distance.
To achieve the above and other objects, the cooling fan according to the present invention includes a seat having a bearing cup internally defining a receiving space, and the receiving space axially extending a full length of the bearing cup; a stator assembly being mounted around the bearing cup; a bearing internally defining a shaft space and being received in the receiving space of the bearing cup; a rotor assembly having a hub and a rotor shaft; the hub having a plurality of blades spaced thereon; the rotor shaft having an end inserted into one side of the hub and another opposite end rotatably received in the shaft space. The rotor shaft has a main body, which includes a central portion and an extension portion. The extension portion includes a plurality of extension sections, which are connected to one another and respectively radially outward extend from the central portion to together define a peripheral surface of the main body. The extension sections respectively radially outward extend from the central portion by a different distance. A lubricant is filled in a space left between the peripheral surface of the main body and the shaft space.
Since the rotor shaft according to the present invention has a non-circular cross section, the lubricant filled in the space left between the peripheral surface of the rotor shaft and the shaft space of the bearing of the cooling fan can have increased support pressure to avoid the occurrence of frictional wearing, noise, and vibration during the operation of the cooling fan, which in turn largely increases the service life of the cooling fan.
The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein
The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.
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The main body 11 has a central portion 111 and an extension portion 112. The extension portion 112 has a plurality of extension sections 1121 connected to one another. The extension sections 1121 respectively radially outward extend from the central portion 111 to together define a peripheral surface 113 of the main body 11. It is noted the extension sections 1121 respectively radially outward extend from the central portion 111 by a different distance, giving the main body 11 a non-circular cross section.
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The stator assembly 22 is externally mounted around the bearing cup 211.
The bearing 24 internally defines a shaft space 241, and is mounted in the receiving space 212 of the bearing cup 211.
The rotor assembly 23 includes a hub 231 and a rotor shaft 1. The hub 231 has a plurality of spaced and radially outward extended blades 232. The rotor shaft 1 has an end fixedly inserted into one side of the hub 231 and another opposite end rotatably received in the shaft space 241. Since the rotor shaft 1 can be any one of the first to the sixth embodiments of the rotor shaft 1 as described above, it is not discussed in details herein. A lubricant 3 is filled in a space left between the peripheral surface 113 of the rotor shaft 1 and the shaft space 241.
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The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.